Lifting jack



Nov. 16 1926. I

' G. T. TRUNDLE, JR

LIFTING JACK Filed 00?. 17.

1924 3 Sheets-Sheet 1 4 uwntoz 1 MAL/- saw Nov. 16 1926.

G; T. TRUNDLE, JR

LIFTING JACK Filed Oct. 17, 1924 3 Sheets-Sheet 2 Nov. 16 1926. 1,607,373

' G. T. TRUNDLE. JR

LIFTING JACK Filed Oct. 17. 1924 s sheets-sheet. 3

'65 JIZMMWQP In 1 amm Patented Nov. 16,1926

STATES PATENT QLFHQE. v

GEOHGE T. TEUN'DLE, 51%., OF OLEVELANILOHIO, ASSIGNOR TO THE GEO. T. TRUNDLE, JP. ENGINEERING COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

LIFTING JACK.

Application filed October 17, 1924. Serial No. 744,165.

This invention is concerned with lifting jacks and relates to jacks of the double telescoping lift bar type. The general object of the invention is the provision'of. a compact low clearance jack of the double bar type having an unusual lift but of small height and which is simple in operation.

Another object of my invention is the D bers and mechanically actuating the elements in seouence and which ma automaticall tele- L 1 n I scope wnen a load is not on the jack, the

telescoping movements being consequent to a manual positioning of the pawls.

A still further object of my invention is the provision of a mechanical construction for a double bar lifting jack wherein the center of gravity of the assumed load upon the telescoping elements will be in a vertical plane extending ratchet teeth on the bar whereby the stresses betwe n the telescoping elements are reduced a. minimum and the friction therebetween atly reduced. (Ether objects. of my invention will here- ;er be set forth in the following deion referring to the, accompanying o. 9; illustrating a preferred form there- The essential characteristics aresummarized in the claims.

In the drawings, Fig. l is a side elevation of a double lifting bar jack embodying the features of my invention, the jack beingillustrated with the telescoping bar members in extended position; Fig. 2 is a front elevation of the jackshown in Fig. 1; Fi 8 is an enlarged cross sectional View taken substantially along the line 33 of Fig. 1;

Fl 4-. is an enlarged cross se tional elevation tanen through the jack standard and lifting" bars substantially along the line 4+4 of Fig. 3; Fig. 5 isa' fragmentary cross sectional view taken through the pawl mechanism substantiallyalong the line 55 of Fig. 4; Fig; 6 is a cross'sectional view taken approximately through the" through the pawl mechanism and jack bar showing the cooperative relation of the pawl members when conditioned to elevate the lifting bar in a step-by step movement; Fig. 7 is a. view similar to Fig. 6 but show ing the cooperative relation of the pawl members when conditioned to lower the lifting bar by a step by step movement.

My invention contemplates the construction of a jack having aystandard of low.

clearance or height. provided with a plurality ofextensible members comprising the lifting barof the jack which may be elevated and lowered in sequence when carrying aload by a pawl mechanism adapted to.

actuate the extensible members in a step by step movement. The constructive features of the jack are such that an unusually long acl: reach may be obtained and which is readily operated upon the application of a small force and the sequential actuation of the telescoping members comprislng the liftm bar mechanlsm takes olace automatically upon the usual actuation of the pawl members by an operating handle.

The arrangement of the telescoping bar members with reference to the standard and the pawl actuating means is such that when the jack bar takes up a load, the thrust of the load is directly upon the lifting pawl.

and operating lever therefor and the saddle for engaging the object to be lifted'is arranged relative to the lifting bar and standard in such manner that the center of gravity of the load will lie in a plane passing through the ratchet teeth on the lifting bar, thus greatly reducing the reactionary forces between the bar elements and between the standard and bar.

shown in the drawings, I accordingly provide a primary rack bar 8 which is formed to be" retained by and slide in a hollow secondary bar member 9 and the latter is formed to slide in the standard 10 and to have teeth in alignment with teeth on the primary. bar 8. The secondary memher 9 is adapted to be locked to the standard 10 while the bar 8 approaches its completely extended position whereupon it is arranged to engage the secondary bar to bring the teeth thereof into engagement with the pawls. The standard comprises a housing member 10 having a base 12 proportioned whereby it will be bisected by a plane extending through the rack teeth of the bars and is provided with a hollow offset portion in the front of the jack which constitutcsa support for a pivot pin l l upon which a soclr ted operating member 15 is pivotally mounted.

The pawl mechanism for actuating the bars may comprise an operating or lifting pawl 18 mounted in the bifurcated end of an oscillatable handle 15 and, adetent pawl 17. A pin 1- also comprises a pivotal 'mountr for the detent pawl. 11 wlnch serves to engage the bar and support the "oad when the lifting pawl 18 is being oper- ;ed by the member 15. The pawl 18 is ivotally" mounted upon. a pin- 19 secured n the'hirurcate'd end of theoperating mem- 381 15. A spring member 20. formed at the lower end thereof to engage the jack standard extends over a pin member 23 and upwardly asuiiicient distance within the housing portion 13 to engage suitable shoulders formed onbothjthe. pawl members whereby they are. normally urged into engagement \Vlllll teeth 25 formed on the front faces of the telescoping rack bar. members 8 and The teeth of the respective rack bar men'ibers .re formed to he in alignment and the pa :1 members 17 and 18 have the rack.

rack bars by the pawl members will now be.

in .li igs. l, 6 and 7, a manually I described. set trip member in the form of a flat lever 30 is shown as being mounted upon the operating lever pivot pin 1%. In these figures, a spring 31 is shown formed to engage the front wall of the standard and extend around the pin 23 and upwardly to engage cam end of the lever member 30. The

sorin as shown in Fin. 4 will retain the 1 z-w a lever as positioned, and in which position the lever 30.does not contact with. the pawl members in any manner when the pawl 18 is actuated to raise the bars. The

oscillating movement of the member 15 will.

raise and lower the pawl 18 and the barv will be elevated at each oscillation thereat a distance corresponding to the pitch of the rack teeth. The pawl 1''? serves merely as a resilient detent to retain the bar in 621i (1.

of its step by step elevated positions. When it is desired to lower the bar by a step by step movement, the trip lever 30 may be manually swung to the position shown Fig. 7, whereupon a cam portion 40' thereof will engage a projection .41 on the pawl 17 to draw it out of engagement with the. rack bar. This manual shifting of the opating handle.

will. lie

20 when the operating member 15 is ow upwardly, thus carrying the opcrat pawl. 18 downwardly with the loaded b in engagement therewith. r-i shoulder formed. on the pawl member 18 contacts .wit the cam portion 32 of the opera member: 30. thus causing the lz-ttter to be swung inunison with. the movement of tl operating member until the pawl 1'? takes so the load... The trip lever 30 has the cam portion 40. thereof shifted from the pro jection 41 on the pawl 17 and the latter is permitted to engage a succeeding tooth on the lifting bar. If no load is on the jack bar, the operating member 15 may be brought into alignment with the trip lever 30, causing downward movement of the inner. ends of both members simultaneously and the pawls will be brought 0' t of 3Y1? gagement with the lifting bars when the lifting bars are freeto drop. It is to be understood that both pawls cannot simultaneously become disengaged from he lillili bars if a load is present on the The mechanical arrangement wher by obtain an efiicient cooperation betw; standard, the intermediate racl; the primary raclr bar 8 will he now set It has been the custom in construct jacks of the rack bar type to position the saddle portion of the reel: bar relative to the bodyof the bar with the center of tx: iv

saddle. arranged pproximately in 7 V v ment w1ththe co r of the l ln the present instance, the saddle poi -n 6 the body of the prirbar 8 a so that the saddle center is direc ment w th the teeth of t e ba T e 12'0f' the standard is also proportioned rela tive to the housing portion of the i l that a vertical plane z exte d the center. of the saddle porti bar 8 bisects the base r of this arrangement in a aclr scoping elements is apparent. rangement, the major thrust etzc the jack is taken directly by the very little friction will exist betw he elements when relative movement is taking place between the two rack bar members 72 which engage the secondary bar 9 in longitudinally extending slots formed there-' in and the standard is provided with interiorly d sposed longitudinal ribs which engage in slots 81 formedin the side walls of the secondary bar 9. In view of the ab scnce of reactive force and a considerable decrease in friction between them due to the position of the saddle 70 on the bar 8, the bar members 8 and 9 may comprise castings and the sliding surfaces thereof may be accordingly more or less rough without interfering with the proper operation of the jack.

The means for automatically locklng the 7 secondary element to'the standard and the primary element to the secondary element will now be described. In Fig. 2 it will be noted that at the upper portion on the front face of the secondary element 9, the teeth are omitted. Then the secondary element 9 is in a completely telescoped position relative to the standard the face portions 90 of the member '9 are adjacent the tooth engaging end of the operat ng pawl 18. Thus the operating pawl engages only the teeth of the primary bar 8 until the primary bar is in an approximately completely extended elevation. Carried on the lower end of the bar 8 is a plunger 92' urged normally rearward by a spring 93 against the inner surface of the back wall of the bar 9. The friction created by the action of the spring 98 would normally cause the bar 9 to follow themovement or the bar 8, but I provide a posit ve stop for the bar 9 in the form of a pivotally mounted detent lever 95. disposed between the back walls of the standard and the bar 8 and extends through a seat form in the bar 9.v The upper edge of this detent lever is formed to engage a shoulder of an opening 96 formed in the back w ll of the standard, the detent be-i mounted upon a pin 97 supported by p 98 formed on the bar 9. The shape ln s ot the detent lever 95 is such that it extends through the slot in the bar 9 with a portion thereof in rubbing contact with the rear face of the bar 8, this rubbing contact be ing such that itis maintained in a' locking position relat ve to the standard as long as it is in contact with the bar 8. It is according ly positioned on the bar 9 a considerable distance below the top thereof whereby the lower end of the inner bar 8 will be elevated out of contact with it prior to the locking of the two bars together. At such time, the plunger 92 carried by the bar'S will have been hrought into alignment with an opening 99 formed in the back wall of the bar member 19, whereupon the two members will become automatically locked together and the first upper teeth on the inner bar member9 will be brought into operativerelation with the operating pawl 18. Both bar members may'thus be actuatedto complete extensible position until a lug 101, formed 'onthe bottom of the bar 9, contacts with the "underside of a transversely disposed plate 102 extending through a suitable open-ng formed in the rear Wallof the standard, the plate being positioned to be in alignment with the opening 99 formed in the bar member 9. A flange bordering the opening 99 is slotted to permit the plate to extend into the open ng whereby the upper side 103 of this plate member may serve as a cam to urge the plunger 92 out of engagement with the bar member 99 upon a downward movement of the bar member. In Fig. 6 the'bar member 8 is shown in a completely extended 'position and locked by the plunger 92 to the bar member 9. It will be noted in Fig. 6 that the locking lever 95 is positioned to be out of longitudinal alignment with the plate member 102, whereby this lever will clear the cam when the bar member 9 is completely elevated.

--From the foregoing description of my invention it will be readily seen that a jack invention will be very compact and sturdy,

while an unusual elevation in the load'lifu' ingmember may be obtained; that these members may be operated in sequence and automatically locked together and unlocked only when each member has been actuated to its full movement relative to the other member and that, the construction is such that the proper automatic telescoping of the members upon the usual manipulation of a jack operating member is assured by .reason of the fact that the load is primarily taken directly on the pawl carried by the operating member thus greatly eliminating the tendencyof the telescoping members to bind together and operate out of sequence.

I claim:

1. A l fting jack comprising a standard a vertically movable lifting'bar mechanism mounted in the standard and formed by pair of telescoping members having adjacently formed rack teeth, an operating member and pawl carried thereby for engaging the teeth of the rack members, means for positively locking one rack member to the standard during a lifting movement of the 2. lifting ,comprising a base ,or standard, a load lifting mechanism vertically movable within the standard, operating means for elevating and lowering said liftsm in step by step movements, 1 echanism comprising a pair of telescooingiy arranged rack bar members having the rack teeth thereof in a common plane, means whereby one rack member is retained in the base while the other is elevated, means for automatically locking the two rack members together upon the complct; sion of one of the members, one

members haying a load receiving nosed thereon whereby the center in a vertical plane extending the rack of'both rack mem- In a lifting jack an extensible bar comrising vertically movable members, operate means adapted to lift one of said memindependently of the other, a latch be s carried by one of said members and adaoted to cooperate with the other ,to permit the members to rise in response to movement of said operating means after one of the members has been lifted a predetermined distance and means operable by one of +he members for maintaining the other member locked to the standard.

4. A lifting jack comprising a standard, a vertical movable lifting bar mechanism nounted in the standard and formed by a pair of telescoping members having adjacently formed rack teeth, an operating member and pawl carried thereby for disengaging the teeth of the rack members, a swingableiiieinber for positively locking one rack member to the standard during a lifting movement of the other rack member, a spring urged plunger carried'by one of the members for locking the two rack members together while the first rack member is approaching a completely extended position relative to the second rack member, said swingable member being released by the fi st ror member prior to the locking toget-her or the two rack members by said plunger and means carried by the standard v the plunger upon the com pletion OJ. a lowering movement of a second rack member.

A lifting jack comprising a base or standard, load lifting mechanism vertically movable within the standard, operating means for elevating and lowering said lifting mec anism in a step by step movement, said hi mechanism comprising a pair of telescopingly arranged rack bar in mbers having the rack teeth thereof in a common plane, means whereby one member is retained in the base vhile the other is elevated, means for lockingthe two rack members together upon the complete extension of one of the members, one of said members having a spring pressed plunger automatically operable to loci; both rack members together i pon a extensible movement of one member and ,to be automatically .retracted upon a full reversefmovement of the other bar member: '4

,6. A lifting jack comprising a standard, a vertically movable'l'iftmg bar'mechanism lably mounted'in the standard and coinp sing a ph rality of telescopingmembers having adjacently formed rack teeth, an opg member, a pawl carried on the inner end of the member, the pawl being of a width corresponding tothe combined width plur lity of telescoping members, a

ever carried one of the telescoping mem bers for engaging the standard, said lever be ng ,eontrohedby another of said telescoping members, whereby the first named member will bemaintained in locked relation to the standard while the second named member'is being elevated to a predeterm ned position relative thereto, a plunger carried said second named memberfthe'first members forfen a inm the standard, said b b b iockingmember being controlled by another of said telescoping members whereby the first named member will be maintained in locked relation to the'standard while the second named member is being elevated to a predetermined position relative thereto, a locking plunger carriedby said second named member, the first named member hav inga "socket for receiving the plunger and a cam for forcing the plunger out of the socket, said cam being mounted on the standard and adapted to extend into the socket of said socketed member when the latter is in its lowered position.

In testimony whereof, I hereunto affix my signature.

.enoren r. Tenants, JR. 

